The present invention relates to a device for investigating the properties of a viscoelastic medium, and more particularly, to a rheometer for measuring the dynamic rheological properties of gels, melts, polymer solutions, and other highly viscous media.
Conventional dynamic rheological techniques involve the forced generation of shear waves of varying magnitude in the medium under investigation and the recording of displacements of a wave-receiving and reflecting surface using a suitable transducing device. Phase and magnitude relationships between corresponding force and displacement waveforms are then analysed to determine the rheological properties of the medium. The major disadvantage of such techniques lies in the fact that accurate determination of the dynamic stresses and strains at measuring geometry boundaries is required to produce meaningful results. Such accurate determination is difficult to achieve at high frequencies.